THE NEARLY-COEVAL BUT METALLOGENICALLY DISTINCT TUNGSTEN-BEARING INTRUSIVE COMPLEXES IN THE SOUTHERN TIEN SHAN: FIRST DATA ON THE ISOTOPE U-Pb DATING (LA-ICP-MS METHOD) OF ZIRCON FROM INTRUSIVE ROCKS OF THE MAIKHURA AND KABUTY TUNGSTEN SKARN DEPOSITS (TAJIKISTAN)

The paper presents first isotopic U-Pb data (LA-ICP-MS method) on zircon from the intrusive rocks of the Maikhura and Farkhob massifs, which the Maikhura tungsten-tin and Kabuty tungsten-polymetallic skarn deposits are associated with. These deposits, together with the other W and Au deposits, are part of the largest Au-W metallogenic belt of Tien Shan. The concordant isotopic U-Pb data for zircon “autocrysts” (302.5 ± 2.3 Ma for granodiorite of the Maikhura massif, 305.1 ± 2.3 Ma and 306.6 ± 2.8 Ma for granodiorites of the Farkhob massif) indicate a nearly-coeval emplacement of these rocks in the Late Carboniferous. The younger (Early Permian) concordant isotopic U-Pb data for zircon “autocrysts” (292.2 ± 2.3 Ma) have been obtained for biotite granites of the Maikhura massif. The metallogenic difference of these deposits highlights the difference of the respective intrusive complexes, whereas the coincidence of the age dates of the intrusive rocks can indicate a nearly-coeval timing of formation of magmatic chambers of different composition at various crustal and upper mantle levels and in a different protolith, which is characteristic of the post-collisional magmatism. Despite of the difference in the composition of the ore mineralization, its relationships to the nearly-coeval igneous complexes may indicate a certain genetic proximity of the tin-tungsten and tungsten-polymetallic-gold metallogenic types that is expressed in post-collisional metallogenic belts globally.